As the honeycomb structural body used in the exhaust gas converting apparatus for vehicles, there is well known a one-piece type honeycomb structure (called as a honeycomb monolith) made of a low thermal expansive cordierite. This type of the honeycomb structural body is used by carrying a material having a high specific surface area such as active alumina or the like, a catalyst of a noble metal such as platinum or the like, and an alkali metal for the NOx purifying treatment on the wall surface.
As another example of the honeycomb structural body, there is also known an aggregate type honeycomb structural body formed by integrally bonding a plurality of honeycomb structural units (honeycomb units) made of a high specific surface area material prepared by extrusion molding a material comprising inorganic fibers and an inorganic binder through adhesion sealing materials (DE 4341159 A1).
Also, there is known a honeycomb structural body used as an exhaust gas converting filter for catching and oxidation removing particulates included in the exhaust gas from vehicles (WO03/067041 A1, WO03/081001 A1).
The contents of DE 4341159 A1, WO03/067041 A1 and WO03/081001 A1 are incorporated herein by reference in their entirety.